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The idea for a heavy infantry support vehicle capable of demolishing heavily defended buildings or fortified areas with a single shot came out of the experiences of the heavy urban fighting in the Battle of Stalingrad in 1942. At the time, the Wehrmacht had only the Sturm-Infanteriegeschütz 33B available for destroying buildings, a Sturmgeschütz III variant armed with a 15 cm sIG 33 heavy infantry gun. Twelve of them were lost in the fighting at Stalingrad. Its successor, the Sturmpanzer IV, also known as Brummbär, was in production from early 1943. This was essentially an improved version of the earlier design, mounting the same gun on the Panzer IV chassis with greatly improved armour protection.

While greatly improved compared to the earlier models, by this time infantry anti-tank weapons were improving dramatically, and the Wehrmacht still saw a need for a similar, but heavier armoured and armed vehicle. Therefore a decision was made to create a new vehicle based on the Tiger tank and arm it with a 210 mm howitzer. However, this weapon turned out not to be available at the time and was therefore replaced by a 380 mm rocket launcher, which was adapted from a Kriegsmarinedepth charge launcher.

In September 1943 plans were made for Krupp to fabricate new Tiger I armored hulls for the Sturmtiger. The Tiger I hulls were to be sent to Henschel for chassis assembly and then to Alkett where the superstructures would be mounted. The first prototype was ready and presented to Adolf Hitler in October 1943. Delivery of the first hulls would occur in December 1943, with the first three Sturmtigers completed by Alkett by 20 February 1944.

Due to delays, Hitler did not request production of the weapon until 19 April 1944; 12 superstructures and weapons for the Sturmtiger would be prepared and mounted on rebuilt Tiger I chassis. The first three production series Sturmtigers were completed by Alkett in August 1944. Plans to complete an additional seven 38 cm Sturmtigers from 15 to 21 September 1944 were presented to Hitler in a conference on 18–20 August 1944. Ten Sturmtigers were produced in September, along with an additional five in December 1944.[2]

Hitler had laid great importance on the special employment of the Sturmtiger and believed it would be necessary to produce at least 300 rounds of ammunition per month.[2]

The Sturmtiger was based on the late model Tiger I, keeping its hull and suspension. The front of the Tiger's superstructure was removed to make room for the new fixed casemate-style fighting compartment housing the rocket launcher. This was located directly at the front of the vehicle, giving it a boxy appearance.

Compared to the Tiger tank, the Sturmtiger was much shorter overall, only 6.28 m (20 ft 7 in) compared to the Tiger's 8.45 m (27 ft 9 in), due largely to the fact that it did not have the long main gun of the latter which protruded far in front of the hull. It also was slightly lower than the Tiger at 2.85 m (9 ft 4 in) compared to 3 m (9 ft 10 in).

Since the Sturmtiger was intended for use in urban areas in close range street fighting, it needed to be heavily armoured to survive. Its sloped (at 47° from vertical) frontal armor therefore was 150 mm (5.9 in) thick, while its superstructure side and rear plates were 82 mm (3.2 in) thick.[1] The hull front was 100 millimetres (3.9 in) or 150 millimetres (5.9 in) if it had an additional armor plate fitted. This pushed the weight of the vehicle up from the 57 t (56 long tons; 63 short tons) of the Tiger I to 68 t (67 long tons; 75 short tons).

The main armament was the 380 mm Raketen-Werfer 61 L/5.4, a breech-loading rocket launcher, which fired short-range, rocket-propelled projectiles roughly 1.5 m (4 ft 11 in) long. There were a variety of rounds with a weight of up to 376 kg (829 lb), and a maximum range of up to 6,000 m (20,000 ft), which either contained a high explosive charge of 125 kg (276 lb) or a shaped charge for use against fortifications, which could penetrate up to 2.5 m (8 ft 2 in) of reinforced concrete. The stated range of the former was 5,650 m (6,180 yd). A normal charge first accelerated the projectile to 45 m/s (150 ft/s), the 40 kg (88 lb) rocket charge then boosted this to about 250 m/s (820 ft/s).

The design of the rocket launcher caused some problems. The hot rocket exhaust could not be vented into the fighting compartment nor could the barrel withstand the pressure if the gasses were not vented. Therefore a ring of ventilation shafts were put around the barrel which channeled the exhaust and gave the weapon somewhat of a pepperbox appearance.

Due to the bulkiness of the ammunition, only 14 rounds could be carried, of which one was already loaded, with another in the loading tray. The rest were carried in two storage racks. To help with the loading of ammunition into the vehicle, a loading crane was fitted at the rear of the superstructure next to the loading hatch. Even then, the entire five man crew had to help with the loading.

It was intended that each Sturmtiger would be accompanied by an ammunition carrier built on the same Tiger I chassis, but only one carrier was completed.[1]

At the loading hatch's rear was located a 100 millimetres (3.9 in) grenade launcher, using Bounding mines, which was used for close range defence against both armoured vehicles and infantry in a 360 degree circle around the vehicle.

For defence against infantry attacks, there was a mount in the front for a 7.92 mm MG 34machine gun.

The Sturmtiger was intended to serve as a heavy infantry support vehicle, rendering assistance with attacks on heavily fortified or built-up areas. By the time the first Sturmtigers were available, however, the situation for Germany had changed for the worse, with the Wehrmacht being almost exclusively on the defensive rather than the offensive.

Three new Panzer companies were raised to operate the Sturmtiger: Panzer Sturmmörser Kompanien (PzStuMrKp) ("Armored Assault Mortar Company") 1000, 1001 and 1002. These originally were supposed to be equipped with fourteen vehicles, but this figure was later reduced to four each, divided into two platoons.

PzStuMrKp 1000 was raised on 13 August 1944 and fought during the Warsaw Uprising with two vehicles, as did the prototype in a separate action, which may have been the only time the Sturmtiger was used in its intended role. PzStuMrKp 1001 (commanded by Captain von Gottberg) and 1002 (commanded by Lieutenant Zippel) followed in September and October. Both PzStuMrKp 1000 and 1001 served during the Ardennes Offensive, with a total of seven Sturmtigers.

After this offensive, the Sturmtigers were used in the defence of Germany, mainly on the Western Front.